Flying model airplane

ABSTRACT

A propellor driven model airplane having a body which is molded of light weight, expanded, cellular plastic material which is capable of self-supporting although incapable of properly supporting a motor per se for driving the propeller of the model airplane. A special, thin walled nose fitting is secured to the nose end of the cellular plastic body and rotatably supports a propeller mounted on the shaft to which is attached one end of a rubber band motor. The other end of the motor is retained by a hook forming part of a special fitting at the tail end of the cellular plastic body. In a particular embodiment, the cellular plastic body is shaped with a channel extending longitudinally therealong which is open substantially the length of the body and provides ample space for accommodating the rubber band motor. In another form, other suitable fittings are also provided for properly securing landing gear to the wings or body of the model airplane.

United States Patent 1 Lemelson 51 Apr. 3, 1973 [54] FLYING MODEL AIRPLANE [76] Inventor:

Street, Metuchen, NJ. 08840 [22] Filed: July 6, 1971 [21] Appl. No.: 160,006

Primary ExaminerLouis G. Mancene Assistant ExaminerRobert F. Cutting Jerome H. Lemelson, 85 Rector [57] ABSTRACT A propellor driven model airplane having a body which is molded of light weight, expanded, cellular plastic material which is capable of self-supporting although incapable of properly supporting a motor per se for driving the propeller of the model airplane. A special, thin walled nose fitting is secured to the nose end of the cellular plastic body and rotatably supports a propeller mounted on the shaft to which is attached one end of a rubber band motor. The other end of the motor is retained by a hook forming part of a special fitting at the tail end of the cellular plastic body.

In a particular embodiment, the cellular plastic body is shaped with a channel extending longitudinally therealong which is open substantially the length of the body and provides ample space for accommodating the rubber band motor. In another form, other suitable fittings are also provided for properly securing landing gear to the wings or body of the model airplane.

l1 Claims, 6 Drawing Figures PATENTEUAPR s 1m INVENTOR. JFROME HLEMELSON FLYING MODEL AIRPLANE SUMMARY OF THE INVENTION This invention relates to new and improved structures in model aircraft, particularly propellor driven model airplanes which are powered by rubber band motors. Foamed cellular plastic material which is light in weight is molded to form at least the body of a model airplane and is of such a shape as to accommodate the rubber band motor in such a manner so as to permit rapid and easy access thereto.

Heretofore, it was known in the art to manufacture propeller driven model aircraft of various material including balsa wood, paper or silk covered wire frames and injection molded plastic of generally thin walled configurations; Balsa wood requires a substantial amount of hand fabrications as does a model having its body and wings made of fabric or silk covered wire in the form of a frame. Conventional injection molded plastic is relatively heavy even in the thinner walled configurations which have been employed to produce flying models and such that the models have poor glid' ing characteristics.

While foamed, cellular plastic materials have been employed to produce gliders and the wings of certain propeller driven models, they have not been heretofore used for propeller driven model airplanes due to the fact that the cellular material is relatively low in tensile and compressive strength and cannot easily accommodate the propeller and motor required to generate thrust. Accordingly it is a primary object of this invention to provide new and improved structures in model aircraft employing a lightweight expanded cellular plastic material.

Another object is to provide a model aircraft body structure having reinforcing fitting means for accommodating a rubber band motor at the ends of the body which fittings may be easily assembled to the body and serve to protect and reinforce the relatively weak cellular structure comprising the major portion of the body.

Another object is to provide an improved body structure in a model airplane which may be easily molded yet which provides an accsesable opening along the length of the body in the form of a channel for accommodating a rubber band motor in such a manner that the rubber band is disposed within the body but access thereto may be easily had by hand for changing or adjusting same.

Another object is to provide an improved lightweight model aircraft structure having a body, wings and tail surfaces which are formed of a single molding, yet which provide quick and easy access to a rubber motor therein.

Another object is to provide new and improved structures in plastic fittings applicable to cellular plastic mode aircraft components.

With the above and such other objects in view as may here after more fully appear, the invention consists of the novel structures and constructions illustrated in the accompanying drawings and described in the specification forming a part hereof but it is to be understood that changes and modifications may be made thereto coming within the purview of the accompanying claims without departing from the spirit and nature of the invention.

IN THE DRAWINGS:

FIG. 1 is an isometric view of a propellor driven model airplane showing structural details of the instant inventions;

FIG. 2 is a cross-sectional view taken through the longitudinal axis of the front portion of the body of a model airplane made in accordance with the features of FIG. 1;

FIG. 3 is a cross-sectional view taken through the longitudinal axis of the body of a model airplane of the type shown in FIG. 1 near the tail end thereof showing further details of the body;

FIG. 4 is a cross-sectional view taken lateral to the longitudinal axis of the body of the model airplane of FIG. 1 just behind the cowling thereof;

FIG. 5 is a sectioned view of a portion of a wing of a model airplane of the type shown in FIG. 1 which illustrates details of a fitting for retaining a wire landing gear in assembly with the wing or body of the model airplanes; and

FIG. 6 is a cross-sectional view taken through the longitudinal axis of a model airplane body at the nose end portion thereof showing further details and modifications in structure.

FIG. 1 illustrates a model airplane 10 the major portion of which is made of a cellular foamed plastic such as expanded polystyrene which is extremely light in weight and which may be easily molded to shape by, for example, the expansion of pellets of such plastic containing a blowing agent when heat is applied thereto in a mold. The model airplane 10 of FIG. 1 contains not only the body 11 made of such expanded, cellular plastic but also the wings 17 and I8, elevator 19 and rudder 21 are also made of such plastic. In a preferred form of the invention, the wings, body and tail surfaces may all be integrally molded in a single, two piece mold by properly distributing and expanding plastic material within the .mold such as the described polystyrene plastic.

In order to accommodate a rubber band motor extending longitudinally through the body 11, a U-shaped channel 11' is formed during molding, longitudinally along the body 11 forming side walls 13 and 14 joined by a relatively thick top wall 12 as illustrated inoFlG. 4. The channel 11' provides not only means for accommodating a rubber band motor longitudinally through the body but also provides access from the bottom of the body to the rubber band motor for changing or adjusting same. The U-shaped configuration also permits the body to be fabricated of relatively large external shape without unduly increasing the weight of the body a degree whereby it may impair the ability of the model to properly glide.

The characteristics of a lightweight expanded plastic applicable for the production of model airplanes such as cellular polystyrene, are such that it will not easily accommodate or support a conventional nose plug or tail hook used, for example, in the construction of balsa wood model aircraft. Expanded polystyrene in the low enough density required for the construction of rubber band powered model airplanes having wing spans in the range of 12 to 24 inches, is generally incapable of supporting a conventional thrust bearing of the type generally used in the construction of conventional powered models. Accordingly, the construction provided in the drawings and illustrated in greater detail in FIGS. 2 and 3, includes a thin walled cowling 23 of cup/-like or parabaloid shape and formed of rigid or semi rigid injection molded plastic or spun aluminum which is mounted at the nose end of the foamed plastic body and which not only supports and reinforces said body at its nose end but also supports a propeller shaft 20 which is made of relatively small diameter music wire extending through a small hole 24 in the forward end of the nose fitting 23. The wire 20 is bent in the shape of a hook 21 at one end and extends through a hole in the hub of the propeller 27 and is secured to said propeller. The hook 21 accommodates one or more elongated rubber bands 20 which extend through suitable adhesive. Preferably the nose fitting 23 may be injection molded of high impact polystyrene although it may also be molded of medium or high density polyethylene or polypropylene.

The tail fitting 28 is also shown as of substantially paraboloid shape, thin walled, and conforming along the inside surface thereof to the outer surface of the tail end 16 of the body 11. The tail fitting 28 may also be frictionally secured to the tail end of the body or adhesively bonded thereto. Said tail fitting is also molded with a hook-like formation 31 for receiving and retaining the tail end of the rubber band motor 30. Also shown protruding downwardly from and preferably integrally molded with the tail fitting 28 is a tail skid 28' for supporting the tail end of the body off the ground.

Illustrated in FIGS. 4 and are details of a fitting 32 adapted to receive and retain a bent wire 35 comprising the main portion of the landing gear of the model which rotatably supports a wheel 36 at its lower end. The wire 35 extends through a holevor channel in a downwardly protruding portion 33 of the fitting 32 and is both laterally and longitudinally supported thereby. Wire 35 is bent at its upper end so that it extends parallel to and adjacent the flat base 32' of the fitting. The fitting 32 is secured to the wings or body of the model airplane by two or more elongated, tapered blades 34 projecting upwardly from the base 32' which blades penetrate into the cellular plastic body or wings and at least partially retain the fitting 32 in place. Adhesive may be provided between the surface of the fitting 32 contacting the cellular body 11 to further secure it in place.

In FIG. 6 the nose end ofa modified model airplane body 40 is shown as being made of a molded expanded cellular plastic body portion 41 having a thin walled, injection molded fitting 44 secured thereto as described. The fitting 44 is molded with a tubular portion 46 extending axially from the nose end 45 thereof for accommodating the propeller shaft 47, as shown, The tubular portion 46 extends through an opening in the expanded plastic material 43 which forms the nose end of the body and, as illustrated, conforms to the entire interior surface of the fitting 44. The cavity of channel 42 in the body 40 thus extends only partially along the length thereof and terminates at the end wall portion 43 of the body. The other end of channel 42 also preferably terminates at an end wall portions similar to 43 which accommodates a tail fitting somewhat like 28 of FIG. 3. Advantages of the structure shown in FIG. 6 over that of FIG. 2 include, in addition to providing additional support for the propeller shaft 47 in the form of the tubular formation 46 also providing additional support for the cowling or fitting 44 in the form of expanded plastic material 43 substantially filling the interior of said fitting.

It is noted that the structures illustrated in FIGS. 1-6 are subject to certain variations including one design in which a channel such as 11 is provided in the upper surface of the body. In another construction, it is noted that the nose fittings 23 and 44 may be molded to accommodate one or more wires defining a landing gear protruding downwardly therefrom. It is also noted that the open channel 11' may contain a separately molded wall or fitting extending between the lower edges of the side walls 13 and 14 and secured thereto to provide addittional strength and support for the lightweight cellular plastic body.Such wall may extend part of the length of the plastic body and be pinned or frictionally fit with the lower edges of the side walls 13 and 14. It may also be cemented to the side walls. The wall enclosing the volume 1 1 may also extend substantially the entire length of the body and be frictionally held in place by the end fittings 23 and 28 which extend over the end portions of said lower wall. The wall may be removable when the end fittings 23 and 28 are removed or cemented to the side walls 13 and 14 of the body 11. The wall denoted 12' in FIG. 2 may be injection molded of the same plastic comprising the nose and tail fittings 23 and 28 or molded of the same cellular plastic comprising the rest of the body 11. It ,12' may also be shaped with protrusions along its length which frictionally engage in cavities 11a in the side walls 13 and 14 of the body to retain it in place along the borders of the side walls of the body 11.

I claim:

1. A model made substantially of lightweight expanded, cellular plastic comprising:

a body, wings and tail flight surfaces secured together and forming a light weight flight structure wherein at least the body is formed of expanded cellular plastic,

said body being shaped with a channel extending longitudinally from the nose end to the tail end of the body and open at least most of the length of the body,

a cup-shaped nose fitting having a thin wall of selfsupporting, non-cellular material and having the inside surface of its wall conforming to and circumscribing the nose end of said cellularbody, means for securing said nose fitting to said body,

a propeller,

a hole through said nose fitting,

a propeller shaft extending through said hole and attached to said propeller and supporting said propeller for rotation at the front end of said nose fitting,

a tail fitting secured to the tail end of said body and including rubber band retaining means,

a rubber band motor secured to said retaining means of said tail fitting and to said propeller shaft,

said body, wings, tail surfaces, fittings and propeller providing a flight structure capable of powered and gliding flight through the atmosphere.

2. A model airplane in accordance with claim 1 wherein said body, wings and tail surfaces are molded in one piece and said channel formed in said body is substantially U-shaped.

3. A model airplane in accordance with claim 1 wherein said tail fitting is also a thin-walled cup shaped member, the inside surface of which conforms to the outside surface of the tail and of said body.

4. A model airplane in accordance with claim 3 wherein said tail fitting is molded of plastic said retaining means for said rubber band, comprises a hook integrally molded with said tail fitting for removeably retaining the end of the rubber band.

5. A model airplane in accordance with claim 1 wherein said channel in said body extends the entire length of said body and said end fittings support the side walls of the body.

6. A model airplane in accordance with claim 1 wherein said channel formed in said body terminates near both the nose end and tail end of said body and said nose fitting circumscribes and abuts the cellular plastic material at the nose end of said body.

7. A model airplane in accordance with claim 1 including a landing gear assembly secured to an expanded cellular plastic portion of said flight structure, said landing gear assembly-having a base conforming to the surface of said cellular plastic portion to which it is secured, and means penetrating said cellular plastic portion from said base to retain said base in assembly with said cellular plastic portion.

8. A model airplane in accordance with claim 7 including means bonding said base to said cellular plastic portion.

9. A model airplane in accordance with claim 7 wherein said penetrating means comprises a plurality of elongated tapered element protruding from said base into said cellular plastic and secured to said base.

10. A model airplane in accordance with claim 1 having a member extending between the walls of said channel in said body and at least partly enclosing the channeL l l. A flying model airplane comprising:

a body, wings and tail flight surfaces secured together and forming a light weight flight structure wherein at least the body is formed of expanded cellular plastic a said body being shaped with a passageway therethrough extending longitudinally from the nose-end of the body to the tail-end thereof and open at both ends of said body,

a cup-shaped nose fitting having a thin wall of selfsupporting, non-cellular material and having the inside surface of its wall conforming to and circumscribing the exterior surface of the nose-end of said cellular plastic body,

means for securing said nose fitting to the nose end of said cellular plastic body,

a propeller,

a hole through said nose fitting,

a propeller shaft extending through said hole and attached to said propeller, said shaft supporting said propeller for rotation at the front end of said nose providing a flight structure capable of powered and gliding flight through the atmosphere. 

1. A model made substantially of lightweight expanded, cellular plastic comprising: a body, wings and tail flight surfaces secured together and forming a light weight flight structure wherein at least the body is formed of expanded cellular plastic, said body being shaped with a channel extending longitudinally from the nose end to the tail end of the body and open at least most of the length of the body, a cup-shaped nose fitting having a thin wall of self-supporting, non-cellular material and having the inside surface of its wall conforming to and circumscribing the nose end of said cellular body, means for securing said nose fitting to said body, a propeller, a hole through said nose fitting, a propeller shaft extending through said hole and attached to said propeller and supporting said propeller for rotation at the front end of said nose fitting, a tail fitting secured to the tail end of said body and including rubber band retaining means, a rubber band motor secured to said retaining means of said tail fitting and to said propeller shaft, said body, wings, tail surfaces, fittings and propeller providing a flight structure capable of powered and gliding flight through the atmosphere.
 2. A model airplane in accordance with claim 1 wherein said body, wings and tail surfaces are molded in one piece and said channel formed in said body is substantially U-shaped.
 3. A model airplane in accordance with claim 1 wherein said tail fitting is also a thin-walled cup shaped member, the inside surface of which conforms to the outside surface of the tail and of said body.
 4. A model airplane in accordance with claim 3 wherein said tail fitting is molded of plastic said retaining means for said rubber band, comprises a hook integrally molded with said tail fitting for removeably retaining the end of the rubber band.
 5. A model airplane in accordance with claim 1 wherein said channel in said body extends the entire length of said body and said end fittings support the side walls of the body.
 6. A model airplane in accordance with claim 1 wherein said channel formed in said body terminates near both the nose end and tail end of said body and said nose fitting circumscribes and abuts the cellular plastic material at the nose end of said body.
 7. A model airplane in accordance with claim 1 including a landing gear assembly secured to an expanded cellular plastic portion of said flight structure, said landing gear assembly having a base conforming to the surface of said cellular plastic portion to which it is secured, and means penetrating said cellular plastic portion from said base to retain said base in assembly with said cellular plastic portion.
 8. A moDel airplane in accordance with claim 7 including means bonding said base to said cellular plastic portion.
 9. A model airplane in accordance with claim 7 wherein said penetrating means comprises a plurality of elongated tapered element protruding from said base into said cellular plastic and secured to said base.
 10. A model airplane in accordance with claim 1 having a member extending between the walls of said channel in said body and at least partly enclosing the channel.
 11. A flying model airplane comprising: a body, wings and tail flight surfaces secured together and forming a light weight flight structure wherein at least the body is formed of expanded cellular plastic , said body being shaped with a passageway therethrough extending longitudinally from the nose-end of the body to the tail-end thereof and open at both ends of said body, a cup-shaped nose fitting having a thin wall of self-supporting, non-cellular material and having the inside surface of its wall conforming to and circumscribing the exterior surface of the nose-end of said cellular plastic body, means for securing said nose fitting to the nose end of said cellular plastic body, a propeller, a hole through said nose fitting, a propeller shaft extending through said hole and attached to said propeller, said shaft supporting said propeller for rotation at the front end of said nose fitting, a tail fitting secured to the tail end of said body and including rubber band retaining means, a rubber band motor secured to said retaining means of said tail fitting and to said propeller shaft, said body, wings, tail surfaces, fittings and propeller providing a flight structure capable of powered and gliding flight through the atmosphere. 